Conventionally known are seat adjusting apparatuses for vehicles, which adjust the height of a seat cushion. In such seat adjusting apparatus, the height of the seat cushion is adjustable upon an operation of an operating lever in cases where an occupant is seated on the seat.
For example, according to a seat adjusting apparatus for a vehicle disclosed in JP2003-93187A (FIGS. 11, 12 and 13), provided are a first clutch mechanism and a second clutch mechanism. The first clutch mechanism transmits an operation force applied to the operating lever to a control member via an input side member connected to the operating lever. When the operating lever is not operated, force transmission between the input side member and the control member is cut off. Further, when the operating lever is operated, the second clutch mechanism transmits the operation force to the output shaft via the control member. When the operating lever is not operated, the second clutch mechanism locks the output shaft against rotation.
In the first clutch mechanism, rollers are arranged in a wedge-shaped space defined between a cam surface provided at the input side member connected to the operating lever and an cylindrical surface of the control member. The control member rotates with the rollers engaged in response to rotation of the input side member. When the operating lever is released from being operated, the input side member is returns to the original neutral position.
However, according to the above-described structure, if the rollers rotate slowly relative to the rotation of the input side member in a situation where the input side member returns, the rollers arranged in the wedge-shaped space wedge-shaped space are occasionally trapped, i.e., engaged, between the cam surface and the cylindrical surface. In order to prevent a rotational error due to such engagement, a play is provided for the rollers in the wedge-shaped space. However, such play causes deterioration in an operation feeling due to a delayed movement of the rollers relative to the operation of the operating lever.
The present invention has been made in view of the above circumstances and provides a seat adjusting apparatus for a vehicle in which an operational performance of the operating member at the neutral position is enhanced.